Spring is finally here and we thought it would be a good idea to brush up on some fundamentals of roasting and brewing your coffee. We tried to tackle some of the more common questions that new and experienced roasters are asking us.
Sour Notes- One of the common problems new roasters describe is sourness in their roasts. The most common reason for this an underdeveloped roast. There has been a trend in specialty coffee toward light roasted coffee lately, and we have seen some professional roasts so light that they are grassy and raw tasting. It seems that lights roasts are almost an over-reaction to the very dark roasts that predominated a few years ago.
Roasting your own coffee gives you the flexibility to achieve those nice lighter roasts, but how light is too light? It is important to roast ALL THE WAY THROUGH first crack for your beans to be palatable and to not run the risk of breaking your coffee mill! Coffee that has not roasted through first crack will still be very dense, too dense to grind well. Coffee becomes more brittle as the roast continues. So how do you determine you have roasted through first crack?
First Crack is that initial loud popping sound and occurs in coffee beans at temperatures between 390-410 degrees fahrenheit. The beans will have gone through the initial browning stage which produces that toasty aroma of baking bread. The appearance is light brown, and mottled, with little expansion, no visible oils and few cracks near the bean tip.
If you cannot see the beans in the roaster try listening for those pops. If you cannot hear the cracks (maybe your air roaster is too loud) try using your other senses. Natural sunlight is best to get a visual idea of the roast level, but bright indoor lighting or even a flashlight can help. Notice the aromatics change throughout the different stages of the roast. If you were to bite down on a bean after it had been roasted through first crack it would be difficult to bite through but it shouldn’t be too difficult. If it is woody and almost impossible to bite through it is likely you ended your roast too early.
Stopping the roast at the end of first crack is considered a City Roast. This is the first point where you can end the roast and your beans will be developed. A city roast enhances brightness and the body of the coffee will be light. This roast can work well to enhance floral or citrus notes but is not ideal for every coffee. In fact many origins don’t taste that great at City roast levels. To be on the safe side focus on stopping your roast after first crack is entirely completed but before second crack begins. If your roaster is not making it to first crack check your ambient temperature; all coffee roasters, and especially air roasters, are susceptible to low temperatures. Low voltage or using an extension cord can lower the power to the roaster and lower the temperature. Does the roaster need to be cleaned or filter need to be changed? Check your manual to make sure you are maintaining your machine properly. With some roasters, like a Freshroast, you can snake a thermoprobe through the top to make sure you are hitting your target temperatures. If the roaster is not getting hot enough, try plugging directly into the wall (no extension cord) and try a different outlet. The Sweet Maria’s Forum is a great resource to find out what other folks are doing to achieve good results even with these issues.
Bitter Notes- The other biggest problem for home roasters can be bitterness. This often is a result of the opposite problem – over-roasting. Try lightening up a bit. How do you know if you are roasting too dark? If your beans almost double in size, if they are dark with an oily sheen and the roast looks and smells smoky then you are roasting too dark. The bite test will reveal a bean that breaks easily and crumbles to dust. Grinding will produce many fine particles. This loss of soluble solids can lead to a thin bitter cup with overly roasty taste and lots of sediment. Most of our beans do not benefit from such dark roasting.
Bitterness can also be a result of too fine a grind, over-extraction, or dirty brewing equipment (use a coffee-specific cleaner to break down those rancid oils). Make sure that the water you are brewing with is between 195-205 degrees for proper extraction. Be sure your grind isn’t too fine and that your brew time isn’t too long. Earlier today we were troubleshooting a bitterness issue with a customer. He brought in his nice medium roast and we brewed it for him using a filtercone. He said it was completely different from what he experienced at home. It turned out he had been leaving the coffee in the Moka Pot too long and the brewed coffee was boiling in the pot, creating a bitter taint. This will also happen if coffee is left on a hotplate too long.
Still not getting the cup you want? Make sure you are using the appropriate roaster [or brewer] to achieve your desired roast level. Many roasters can do a full range of roasts with a few exceptions. For instance achieving a medium roast on a whirley pop can be difficult, some of the beans are likely to get scorched or at least roast unevenly. Some roasters have safety features so they do not get too hot, consult the specifications of your roaster if this might be the issue. Also make sure the brewer you are using is appropriate for the cup you want to achieve; for example, a french press will give you very different results than a Chemex. Both have their appeal but might not suit you.
The upside of sourness and bitterness
Some flavor characteristics can be difficult to describe and culturally we are not well versed in communicating sensory experiences. I have noticed that occasionally people confuse the term acidity with sourness. There are beans that are acidic, which is a flavor attribute (rather than a high PH level). Here we are referring to a flavor attribute of a bean, e.g. Kenyas will often have wonderful citric acidity, which could be described as nippy or piquant. Sour is a term used to describe a flavor taint from underroasting or under-extraction when brewing. Bitter flavor characteristics can be the result of too dark a roast, or a flavor taint from brewing. There are bitter flavor characteristics (such as bitter chocolate) that are desirable. Think of arugula or balsamic vinegar for desirable bitterness. You might be doing everything right but you just need to pick coffee that is more suited to your tastes.
Degree of roast is a personal preference, of course. If you are unsure about how dark to roast, try sticking to a City+ through Full City roast, which is usually a safe bet for well defined body, sweetness and acidity. You will notice that stopping the roast in between first and second crack, drawing out that roast time, or stopping just into second crack works for most coffees. The most important thing to remember is to roast completely through 1st crack.